21261021722142 has 16 divisors (see below), whose sum is σ = 42524957485200. Its totient is φ = 7086521567232.

The previous prime is 21261021722137. The next prime is 21261021722167. The reversal of 21261021722142 is 24122712016212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121323517 + ... + 121498632.

It is an arithmetic number, because the mean of its divisors is an integer number (2657809842825).

Almost surely, 2^{21261021722142} is an apocalyptic number.

21261021722142 is an abundant number, since it is smaller than the sum of its proper divisors (21263935763058).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21261021722142 is a wasteful number, since it uses less digits than its factorization.

21261021722142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242836747.

The product of its (nonzero) digits is 10752, while the sum is 33.

Adding to 21261021722142 its reverse (24122712016212), we get a palindrome (45383733738354).

The spelling of 21261021722142 in words is "twenty-one trillion, two hundred sixty-one billion, twenty-one million, seven hundred twenty-two thousand, one hundred forty-two".